Improvement in the construction of outlet guide devices for centrifugal pumps or blowers



A. BUCHI 2,634,685 ROVEMENT IN THE CONSTRUCTION OF OUTLET GUIDE DEVICESFOR CENTRIFUGAL PUMPS OR BLOWERS 4 Sheets-Sheet l w w 3 9 5 1 9 l m 4 1a ALFRED BUCHI 2,634,685 LET GUIDE ERS April 14, 1953 A. BUCHIIMPROVEMENT IN THE CONSTRUCTION OF OUT DEVICES FOR CENTRIFUGAL PUMPS ORBLOW 4 Slgeets-Sheet 2 Filed Feb. 16, 1950 aflnununu HUDUDD J i 4 ALFREDBUCHI April 14, 1953 A BUCHI 2,634,685

IMPROVEMENT IN THE CbNSTRUCTION OF OUTLET GUIDE DEVICES FOR CENTRIFUG'ALPUMPS OR BLOWERS 4 Sheets-Sheet 3 Filed Feb. 16, 1950 Patented Apr. 14,1953 2,634,685 IMPROVEMENT IN THE CONSTRUCTION OF OUTLET GUIDE DEVICESFOR CENTRIFU- GAL PUMPS OR BLOWERS Alfred Buchi, Winterthur, SwitzerlandApplication February 16, 1950, Serial No. 144,408

2 Claims.

This invention relates to improvements in the construction of outletguide devices for centrifugal pumps and blowers, such as are describedin my United States Patent No. 2,596,646.

The unusual shape and arrangement of such guide-devices render theirmanufacture by recognized methods exceedingly difficult and costly.Thus, conventional sand casting of these devices produces inner wallswhich are relatively rough. In pumps or blowers productive of high gasor fluid velocities, such roughness in the guidedevices tends to affectseriously the efiiciency of the machines. It becomes necessary,therefore, to attempt to smooth and polish the inner walls of the sandcast guide-devices. This is a difiicult task, however, as will beobvious from a study of the shaping and arrangement of such devices in ablower or pump casing.

My invention consists of a construction of such guide-devices andarrangements thereof within a casing whereby guide duct walls areprefabricated of relatively thin-walled sheet metal material at leastfor the inner parts of the ducts through which the pressure medium ispassed at high velocity, and in which such velocity is transformed atleast partly into pressure; such prefabricated walls are then set intoposition with moulds for the housing; and casting material is thereuponpoured to form integrally with the prefabricated walls, the desiredhousing and guidedevices.

By this construction the important guide ducts may be provided with thebest possible surfaces by pressing, bending, welding, machining, etc.the thin-walled sheet material prior to its being cast in the housingmoulds.

The design may be such that the inner individually prefabricatedguide-device parts are rigidly joined together in an arrangement to constitute a single piece or several pieces before they are cast into theother part or parts of the bloweror pump-housing.

The inner individually prefabricated guidedevice parts may be cast-in asparts separated by a plane normal to the axis of the machine withlikewise separated cast housing parts. It is also a part of my inventionto fabricate the guidedevice insert parts with edges which protrude overthe final separating plane and the surface of the cast casing parts soas to prevent any overflow of the liquid casting material into the ductsduring the pouring stage of the casting operation. These guide-deviceparts may also be provided with temporary partition walls to close theirnormally open apertures in order similarly to prevent the liquid castingmaterial from flowing Switzerland February 17, 1949 into the ductsduring the pouring operation. After setting, the temporary partitionwalls are removed.

Furthermore, cores consisting of metal or sand o similar material may beprovided inside the guide part inserts for cooling and reinforcing themwhen they are heated during the casting operation. Such cores may alsobe equipped with special cooling devices.

Figs. 1-12 illustrate several executions of my construction. I

Figs. 1-3 illustrate an execution of the invention in which aprefabricated guide-device is disposed in two housing parts, separatedby a plane containing the axis of the machine. Fig. 1 is a side-view ofthe separate housing parts viewed in the direction of the arrow shown inFig. 2. Fig. 2 is a section through the axis of the separate housingparts indicated by the line II--II in Fig. 1. Fig. 3 is a sectionthrough a duct of the guide device taken along the line III-III in Fig.l, as a straight projection.

Figs. 4-6 show an execution of the invention inwhich the prefabricatedguide-device comprises two parts separated by a plane transverse to themachine axis. Fig. 4 is a fragmentary elevation of the separating planeas viewed in the direction indicated by the arrow in Fig. 5. Fig. 5 isa.

section through the axis of the machine according to the line V-V inFig. 4. Fig. 6' illustrates a section through a guide-duct according tothe line VI-VI in Fig. 4, as a straight projection.

Figs. 7-9 illustrate a housing and guide-device in which the individualguide-device parts and housing are also separated by a plane transverseto the machine axis. These illustrations, however, show the appearanceof the parts and hous ing after the casting-in operation and prior totheir being finished and assembled as shown in Figs. 4-6. Fig. 7 is anelevation of the separating plane as viewed in direction of the arrowindicated in Fig. 9. Fig. 8 is an axial section through one half of theguide-device part along the line VIII-VIII in Fig. 7. Fig. 9 is asection taken on the same plane as Figure 8, but looking in the oppositedirection.

Fig. 10 shows according to Fig. 8 the placing of cores in the insertsand other portions of the ducts, and also hollow portions by a sectionthrough the casting box with the moulds and the inserts properly placedand after the casting material has been poured.

Fig. 11 shows according to Fig. 9, in a similar section to that shown inFig. 10, cooling devices placed in the inserts. Fig. 12 shows, in a partsection of that shown in Fig. 9 or 11, the application of metal platingdesigned to fuse with the casting material.

In Figs. 1 to 8, the reference characters I and 2 designate the twohalves of the housing which contain the guide-device. The impellor rotor3 is shown'within the housing rotatably mounted upon a :shaft 8. 54'designatesthe. ducts of the guide-device. The fluid velocity producedby the rotor 3 is transformed into pressure in the ducts 4. My presentinvention calls for, .prefabricatin special walled-inserts 5 toformsductsfl. These inserts are made individually and to' very accuratedimensions and shapes by pressing, bending, welding, machining etc. thinsheet material. These prefabricated inserts 5 protrudewith their openportions 6 over the side walls of the housing parts I and 2 and are castin this condition into the parts of the housing. This serves the purposeof preventing theliquid casting material from .flowing into theseinsertsduring the pouring process. -Af-ter .-the.casting operationiscompleted, the parts 6 which protrude beyond the width-of the housingare cut to their final planar condition coincident with that of thesurface of the cast housing.

Each insert 5 which forms a duct '4 is brought together with adjacentinserts 5 at the edges 1 in such a manner as to form an accuratelyarranged guide-device. upon which no further shop work need be performedto obtain properly dimensioned and shaped ducts. Moreover, thearrangement is-such-as to prevent the liquid castingmaterial fromflowing over into the ducts.

. Prior to the casting-in operation, the inserts 5 may be joinedtogether to constitutea single piece including all guide ducts 4.

In .Fig. 3, 51is the thin-walled insert for the housing part 2. Themanner in which the insert 5 protrudes beyond the housing at 6 previousto the finishing operation is also shown.

In preparation for the casting operation, cores of sand or'metal may beplaced in the inserts 5 for cooling and as reinforcement of the inserts.

In- Figs. 4, 5 and 6, the reference numerals I and. 2' designate thehousing parts of the guidedevice, which parts are. formed as castings.3' is the rotor or impellor driven by the shaft-8. 4' are the ducts ofthe guide-device shaped as diffusers. In these ducts the velocityimparted to the fluid by the rotor 3 is transformed into pressure.5"arethe prefabricated inserts which consist of-thin-walled material andhave been produced before the casting-in operation as parts of thehousing. 9 is the scroll case with the discharge connection [0 shownindash dottedxlines. The. guide ducts 4 enter inlateral direction into the'openings I l. of the scroll case.

In theFigs. 4-6 all parts areshown finished and in assembled condition.I

InFigs. 7-9, the numbers I and 2" designate the two castings which formthe housing parts containing'at least part of the guide ducts 4".

The two thin-walled inserts 5" which form the ducts 4" protrude over theside walls at 8" of the parts I" and 2''. These protrusions of theinserts. 5" are provided for the purpose already mentioned of preventingthe liquid casting material during the casting process from flowing intothe inside'of the .inserts. After the casting operation, the parts I"and 2" are machined and finished in the manner illustrated in Figs. 4-6.

Fig. 7 indicates in dash-dotted lines how the apertures of the inserts 5casting operation by sheet .83 also to prevent the flow are closedbefore the metal partitions l2, of casting material into the inside ofthe ducts. It is evident that Without these partitions the inner surfaceof the inserts 5" would be spattered with casting material. Thispossibility is eliminated by closing the apertures of the inserts in thefashion described. A cooling arrangement for individual guide-devicesmay be provided also as is indicated by dotted lines in Fig. 7. I6 isthe inlet and I9 the outlet of the cooling pipe [7, I8.

In Fig. 10 the cast housing 2" conditioned in the two-part and firmlybolted together casting box 25, 26 designates the moulds 2'! and 28. Theprefabricated insert 5" forms a part of the mould 28, and is anchored tothe insert by temporary ties or anchors 29. The inserts 5 are alsofilled at IS with moulding material, providing for reinforcement of thecomparatively thin sheet metal material of which the inserts are made.At 20 a distinct core of moulding material for forming the guide-deviceportion is shown, but one which is not lined by the prefabricatedinsert. 2| is also a distinct core which forms the hollow spaces of thecasing 2" which has just been poured. The moulds 2'! and 28 may be madeof any suitable material such as sand, iron, etc. The liquid castingmaterial is poured through the opening 30 in the casting box, atsuitable places. At 3| an overflow for the liquid casting metal isarranged, so that a certain maximum level of the liquid metal isguaranteed. The casting material may be poured .under artifical pressurecondition or just ordinarily, or in any other fashion. At 24 a screw isshown in condition to keep the two-part casting box 25, 26 rigidlyclosed during the pouring operation.

The cores may include a special coolingdevice. This is shown in Fig. 11whereat IS the feed piping for the cooling medium is indicated. Thecooling is indicated by pipes l7, l3 placed within the inserts.continuous circulation of the cooling medium. For this purpose to I8 maybe provided for continuous circulation which is indicated in Fig. 7 by asmall arrow.

r The cooling medium is leaving the pipe 18 via the pipe connection I9.

The characters used in Figs. 10 and 11 relate more particularly to.the'execution of guide-devices built as described in Figs. 7-9. Theyare, however, drawn to the principle involved and appertain also to theexecutions of guide devices described in theFigures 1 to 3' and 4' to 6.

During casting, duct portions and other hollow spaces which are notlined by. the inserts 5" are filled out with cores of sand, metal orsimilar material, see Figure 10. The inside of the/inserts 5" may alsobe filled with. cores of metal, sand or similar material to cool and tosupport the walls of the inserts during the casting -operation. Alsoseparate cooling devices referred to and shown in Figs. 11 and 7 may bebuilt'into said cores to provide additional coolingof the in sertsduring casting.

The main advantage proffered by this invention is the elimination of thenecessity of performing additional shop work after the. casting.

operation to attain accurately dimensioned ducts for the guide-devices.Moreover, the inserts 5. 5 and5" are initially provided with smoothinner surfaces. They are also prefabricated :and produced individuall byaccurate tools facilitating their manufacture to precise dimensioning.

If necessary, may be further improved after they have been cast-inthe'housing,

The arrangement provides for means to connect the pipes H;

the inner surfacesof the inserts e. by rinding or polish-1' ing, etc.However, if the'inserts 5, 5', 5" are properly and carefullyprefabricated, no further elaborate inside finishing work should benecessary.

The prefabricated cast-in guide-device is preferably provided on itssurface which is to protrude into the casting with a coating which iscapable of fusing with the casting material. Such fusing tends toestablish undetachable rigid integral contacts of the guide-devices withthe housing or casing. This coating may consist of metal plating, suchas copperand/or tinplating. This is shown in Figure 12, designating at32, said coating on the surface of the prefabricated inprotruding intothe cast housing part I", and fusing with its material, when pouring itinto the mould. Fig. 12 is a partial enlargement of the section shown inFig. 9.

I claim:

1. As an article of manufacture, a housing for a rotatable blower wheeladapted to discharge pressure fluid centrifugally outwardly from theblower wheel axis, said housing comprising two halves of cast materialdivided along a plane substantially normal to the rotor axis and passingthrough the blower wheel, the mating sides of each of said halves beingshaped to provide a portion of each of a series of guide duct diffuserwalls and of a receiving scroll wall, said diffusers originating in thevicinity of the periphery of said blower wheel and being disposed tocontinue the fluid in the direction of its discharge from the blowerwheel for at least some distance, thereafter delivering the fluid intothe scroll, and a smooth-walled metal liner inserted in that area ofeach portion of the guide duct diffuser wall beginning at the fluidentrance where its velocity is highest and continuing for some distancethereafter until a substantial conversion of fluid velocity intopressure has taken place, the said portions so forming the guide ductdiffuser walls and receiving scroll and the smooth-walled metal liner ineach housing half being further so disposed and of such extent as toregister with the corresponding wall and scroll forming portions andliner in the other housing half when the two halves are brought togetheralong said, plane, thereby to completely define a series of guide ductdifiuser passages and scroll, and means for securing said halvestogether in such registry.

2. The housing as defined in claim 1 wherein all the metal linersinserted in one of the halves of cast material are secured together.

ALFRED BUCl-II.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,234,878 Corvin July 31, 1917 1,286,654 Kralund Dec. 3, 19181,652,468 Catlin Dec. 13, 1927 1,799,991 Sellick et al. Apr. 7, 19311,934,239 Schupp Nov. 7, 1933 1,985,341 Fraser Dec. 25, 1934 1,989,996Mautsch 1 Feb. 5, 1935 2,109,680 Neveling, Sr. Mar. 1, 1938 2,157,892Godfriaux May 9, 1939 2,207,317 Gear July 9, 1940 2,224,337 BostwickDec. 10, 1940 2,227,500 Johnson et al Jan. 7, 1941 2,311,024 Buchi Feb.16, 1943 FOREIGN PATENTS Number Country Date 240,220 Great Britain Sept.24, 1925 955,464 France June 27, 1949

